Forgive me for asking such a simple question, I understand why you would want to rel nofollow untrusted links (forum posts, blog comments etc), but why would you not want to do it on EVERY link on your website?

I know it's greedy and perhaps unethical, but if I write a blog post and link to an interesting website within that post, am I losing out in any way by not rel nofollowing it? Is my juice leaking?

It is not greedy but selfish. Every link gives out juice but nofollow links wasted it. Wikipedia does this to keep its dominance over information, even sources (from which the articles are written and often required to have) do not get any juice.
–
ItaiJul 20 '11 at 19:31

4 Answers
4

The answer is you should allow links that are trusted to not have the rel no follow tag. There are a couple of reasons:

Your link juice is always divided between all the links on your page including, the links with the rel no follow tag. The link juice just isn't sent to through the links to the external sites with the no follow tags. The point of rel no follow is to help Google which in the end helps you.

Google does not penalize you for using all no follow links. See the video by Matt Cutts from 2011 about it. That being said, having quality external links does play into Google's algorithm, you just won't be negatively effected by not having any.

According to Matt Cutts links to quality external sites is part of Google's algorithm.

Not to mention, if every site did this imagine what the state of search engines would be like? Quality of search results would suffer tremendously. Be a good webmaster and help the search engines do a better job.

Your link juice leaks out because of any link you place on your page, even if the link uses the rel="nofollow".

The only difference using nofollow affects the destination of the link:

the destination website of a nofollow link won't get any link juice, but that link on your page still leaks out your link juice, that instead of propagating to the link's destination it simply evaporates.

When the the outbound link is to a site that doesn't compete in my industry or topic of interest, then there should be no worry about sending link juice to that site. Just avoid linking to your competition in the SERPs.